Device for detecting a running surface for vehicle and vehicle using same

ABSTRACT

The invention concerns a device for detecting a running surface for vehicle, comprising a plurality of sensors designed to be oriented towards the running surface to determine modifications thereof, means for processing the data concerning information picked up by the sensors, wherein at least part of the sensors are relatively arranged such that at least the transverse distances separating two adjacent points of aim on the ground of the sensors increase towards a longitudinal axis and along a direction substantially perpendicular to this axis. The invention also concerns a vehicle using this device.

The invention relates to a device for detecting a running surface forvehicle and to a vehicle using such a detection device.

The invention concerns more particularly a detection device comprising aplurality of sensors designed to be oriented towards a running surfaceto determine modifications thereof, as well as means for processing thedata concerning information picked up by the sensors.

Document EP 860001 describes such a detection device applied to avehicle and using infrared sensors in order to signal to a vehicle usera possible change in the running surface or the crossing of a markingline on the ground.

Operation of this type of device is globally satisfying, but in somecases, it does not enable detecting with sufficient quality all themodifications of the running surface.

An object of the present invention is to propose a device for detectinga running surface having an improved detection ability with respect tothe prior art, while having a simple and cost-effective structure.

To this effect, the device according to the invention, which isotherwise conform to the generic definition provided in the preambleabove, is essentially characterized in that at least part of the sensorsare relatively arranged such that the transverse distances separatingtwo adjacent points of aim on the ground of sensors increase in thedirection of a longitudinal axis and along a direction substantiallyperpendicular to this axis.

Moreover, the invention can include one or several of the followingfeatures:

-   -   the device comprises at least five sensors,    -   the sensors are located on both sides of a median longitudinal        axis, and the transverse distances between the points of aim on        the ground of the sensors are substantially symmetrical with        respect to this axis,    -   the transverse distance dn in cm separating two adjacent points        of aim on the ground of sensors is given by the formula        dn=k.R^(n), where n is the serial number of the point of aim on        the ground in the direction of the longitudinal axis, R is a        first constant multiplicative coefficient comprised between        about 1 and about 20, and k is a second constant coefficient        comprised between about 5 and about 50,    -   the transverse distance dn in cm separating two adjacent points        of aim on the ground of sensors is given by the formula        ${{dn} = {{L2} \cdot \left( \frac{E + {L1}}{E + {2c}} \right)^{n}}},$        so as to detect in particular a discontinuous marking line on        the ground, and where n is the serial number of the point of aim        on the ground in the direction of the longitudinal axis, L1 is        the length in cm of a dash of the discontinuous line, L2 is the        width in cm of a dash of the discontinuous line, E is the        distance in cm separating two consecutive dashes, and c is a        determined constant defining a detection security margin in cm.

Another object of the invention is to propose a vehicle using such adetection device and remedying all or part of the drawbacks of the priorart.

To this effect, the vehicle according to the invention, comprising aplurality of sensors oriented towards the running surface, to determinemodifications thereof, means for processing data concerning informationpicked up by the sensors, is characterized in that at least part of thesensors are relatively arranged such that the transverse distancesseparating two adjacent points of aim on the ground of sensors increasefrom the outside towards the inside of the vehicle along a directionsubstantially perpendicular to the median longitudinal axis of thevehicle.

Moreover, the invention can include one or several of the followingcharacteristics:

-   -   the sensors are located on both sides of the median longitudinal        axis of the vehicle, and the transverse distances between the        points of aim on the ground of the sensors are substantially        symmetrical with respect to this axis,    -   the transverse distance dn in cm separating two adjacent points        of aim on the ground of sensors is given by the formula        dn=k.R^(n), where n is the serial number of the point of aim on        the ground in the direction of the longitudinal axis, R is a        first constant multiplicative coefficient comprised between        about 1 and about 20, and k is a second constant coefficient        comprised between about 5 and about 50,    -   the transverse distance dn in cm separating two adjacent points        of aim on the ground of sensors is given by the formula        ${{dn} = {{L2} \cdot \left( \frac{E + {L1}}{E + {2c}} \right)^{n}}},$        so as to detect in particular the position of the vehicle with        respect to a discontinuous marking line on the ground, and where        n is the serial number of the point of aim on the ground of a        sensor from the outside toward the inside of the vehicle, L1 is        the length in cm of a dash of the discontinuous line, L2 is the        width in cm of a dash of the discontinuous line, E is the        distance in cm separating two consecutive dashes, and c is a        determined constant defining a detection security margin in cm,    -   the vehicle comprises eleven sensors,    -   at least part of the sensors are oriented laterally towards the        outside of the vehicle,    -   at least part of the sensors are inclined with respect to the        vertical at an angle substantially equal to or above the        half-angle of their cone of vision,    -   at least part of the sensors are inclined with respect to the        vertical at an angle comprised between about 5 and about 45        degrees,    -   at least part of the sensors are disposed in the front bumper of        the vehicle.

Other particularities and advantages will appear while reading thefollowing description made in reference to the drawings in which:

FIG. 1 is a schematic top view of a vehicle on a road,

FIG. 2 is a schematic and partial front view of a vehicle illustrating afirst arrangement of detection sensors according to the invention,

FIG. 3 is a schematic top view of the front portion of a vehicleillustrating the repartition of the points of aim on the ground of asecond preferred arrangement of detection sensors according to theinvention,

FIGS. 4 and 5 show respective third and fourth repartitions of thepoints of aim on the ground of detection sensors according to theinvention,

FIG. 6 is a block diagram of an example of structure and operation of adetection device according to the invention.

The device for detecting a running surface according to the inventionillustrated in particular on FIGS. 2 and 6 comprises a plurality ofsensors c1 to cn connected to means 2 for data processing, such as acomputer.

In the embodiment described above, the sensors are mounted on a vehicle1 and oriented towards the running surface 4 to detect modificationsthereof, and in particular the apparition of markings on the ground. Theprocessing means 2 are constituted, for example, by a computer of amultiplexed network of the vehicle 1.

According to the invention, the vehicle 1 comprises a plurality ofsensors arranged relatively such that the transverse distancesseparating two adjacent points of aim on the ground increase from theoutside towards the inside of the vehicle 1 along a directionsubstantially perpendicular to the median longitudinal axis 5 of thevehicle.

Indeed, surprisingly, such an arrangement of sensors confers an improveddetection quality, as compared to prior art systems. In particular, itis observed that the invention enables a more secure and morecomprehensive detection of a discontinuity in the surface and inparticular a marking line on the ground.

In the embodiment shown on FIG. 2, the vehicle comprises four sensors c1to c4 distributed with one half on each side of the vehicle 1. Eachsensor c1 to c4 has a surface or point of aim on the ground,respectively v1 to v4. Preferably, the four sensors c1 to c4 arearranged in a substantially symmetrical manner with respect to themedian longitudinal axis 5 of the vehicle. The two points of aim on theground v1, v2 or v4, v3 of the sensors located on a same side of thevehicle are, for example, separated by a distance of about 8 to about 25cm, and preferably about 12 cm. The points of aim on the ground v2, v3of the sensors c2, c3 closest to the median longitudinal axis 5 are, fortheir part, separated by a distance of about 1 m to 1.8 m.

In variant, and preferably, the device according to the inventioncomprises at least five sensors, so that the arrangement of FIG. 2 canbe modified by adding an additional sensor in the area of the medianlongitudinal axis 5 of the vehicle. The point of aim on the ground ofthe fifth sensor can be located at the same distance from the points ofaim v2, v3 on the ground of the two adjacent sensors c2, c3.

In another advantageous variant, the transverse distance dn in cmseparating two adjacent points of aim on the ground vn, vn+1 of thesensors is given by the formula dn=k.R^(n), where n is the serial numberof the point of aim on the ground from the outside toward the inside ofthe vehicle, R is a first constant multiplicative coefficient comprisedbetween about 1 and about 20, and k is a second constant coefficientcomprised between about 5 and about 50.

As before, this arrangement confers an improved detection as compared toprior art systems, while combining structural simplicity and low cost.

In yet another advantageous variant, the positioning of the sensors canbe adapted in particular to the detection of discontinuous marking lineson the ground. Thus, the transverse distance dn in cm separating twoadjacent points of aim on the ground vn, vn+1 can be given by theformula${{dn} = {{L2} \cdot \left( \frac{E + {L1}}{E + {2c}} \right)^{n}}},$where n is the serial number of the point of aim on the ground vn of asensor from the outside towards the inside of the vehicle, L1 is thelength in cm of a dash 6 of the discontinuous line, L2 is the width incm of a dash 6 of the discontinuous line, E is the distance in cmseparating two consecutive dashes 6, and c is a determined constantdefining a detection security margin in cm (FIG. 1).

The detection security margin is selected arbitrarily as a function ofintended applications and of the detection precision desired. Thesecurity margin c constitutes the minimal monitoring distance on theground by a sensor from which a change can be considered a possiblemarking. This is to say that the security margin c acts like afilter-forming distance, so as not to take into account small objectspresent on the running surface 4, such as papers. The security margin ccan be fixed to a value comprised, for example, between 0 and 50 cm,preferably about 20 cm.

This arrangement of sensors according to the invention enables a securedetection of modifications in the running surface of the vehicle 1, andis well adapted in particular to the detection of a discontinuousmarking on the ground.

In particular, it has been observed that such an arrangement enables asecure and early detection of a drifting by a vehicle with respect toits trajectory, in particular with respect to a discontinuous line of amarking on the ground. Indeed, when the vehicle drifts from itstrajectory with a low incidence angle, and when the running surfacechanges (for example, crossing a discontinuous marking), the sensorshaving points of aim on the ground v1, vn disposed the farthest to theoutside of the vehicle detect this situation. A drifting with a slightlyhigher incidence angle is detected by the subsequent sensors havingpoints of aim v2, vn−1 in the direction of the inside of the vehicle,and so on.

This is to say that it has been observed that, the lower the incidenceangle of the vehicle with respect to a border (discontinuous marking ofother modification of the surface), the more the detection is made bysensors having points of aim on the ground located outside the vehicle.This detection by the so-called “outside” sensors enables an earlydetection of a possible drifting by the vehicle with respect to itstrajectory.

In order to scale the device so as to detect any discontinuous markingon the ground, i.e., so that it adapts itself to the different markingsin different countries, one can use the formula${{dn} = {{L2} \cdot \left( \frac{E + {L1}}{E + {2c}} \right)^{n}}},$while fixing the width of a dash L2 to its lowest possible valueencountered.

Similarly, the factor $\frac{E + {L1}}{E + {2c}}$is fixed to its lowest possible value encountered.

Thus, in the case of most European countries, the minimal width L2 of adash is in the order of 10 cm whereas the factor$\frac{E + {L1}}{E + {2c}}$is substantially equal to 1.2 (security margin fixed to 20 cm). Thus, ina particularly advantageous embodiment, the transverse distance dn in cmseparating two adjacent points of aim on the ground vn, vn+1, can begiven by the formula: dn=10×1.2^(n).

The vehicle shown on FIG. 3 comprises eleven sensors located in thefront fender 8 of the vehicle, in front of the front wheels 3 of thevehicle, and in accordance with the formula above. The eleven sensorsare only symbolized by their corresponding points of aim on the groundv1 to v11.

Thus, the distance d1 between the first v1 and second v2 points of aimon the ground is substantially equal to 12 cm; 1 a distance d2 betweenthe second v2 and third points of aim on the ground v3 is substantiallyequal to 14.4 cm; the distance d3 between the third v3 and fourth v4points of aim on the ground is substantially equal to 17.3 cm; thedistance d4 between the fourth v4 and fifth v5 points of aim on theground is substantially equal to 20.7 cm; and the distance d5 betweenthe fifth v5 and sixth v6 points of aim on the ground is substantiallyequal to 25 cm. In such a construction in which there is an odd numberof sensors, a point of aim on the ground v6 is located substantially inthe area of the median longitudinal axis of symmetry.

The points of aim on the ground v11 to v6 located on the other side ofthe median longitudinal axis 5 of the vehicle are arranged in asubstantially symmetrical manner with respect to this axis 5 (d10=d1).

FIGS. 4 and 5 illustrate two other examples of arrangements of detectionsensors comprising nine and eight sensors, respectively, disposedsymmetrically with respect to respective axes 5 of symmetry.

In the embodiment of FIG. 4, the successive transverse distancesseparating the adjacent points of aim on the ground v1 to v5 in thedirection of the axis 5 can be substantially equal to 12 cm; 14.4 cm;17.3 cm; and 45.7 cm, respectively.

In the embodiment of FIG. 5, the successive transverse distancesseparating the adjacent points of aim on the ground v1 to v5 an thedirection of the axis 5 may be substantially equal to 12 cm; 14.4 cm;17.3 cm; and 90 cm, respectively.

According to the invention, the sensors cn and thus, their points of aimon the ground vn can be arranged indifferently along directions parallelto the longitudinal axis 5 of the vehicle. Preferably, however, thesensors cn and thus their points of aim on the ground vn are located inthe front portion of the vehicle, so as to detect a variation in therunning surface 4 as early as possible. Similarly, the sensors can bedisposed in any other portion of the vehicle, for example, in the rearview mirrors. Additionally, in other applications, the device cancomprise more than eleven sensors (in particular in the case of atruck).

The above-described sensors are preferably constituted by systemscomprising wave emission means in a range that is little disturbed bylight, for example, infrared waves, and means for receiving thereflected waves. Of course, these infrared sensors can be replaced by orjuxtaposed with ultrasound sensors and/or video sensors or any otherequivalent system.

Of course, the invention is not limited to the embodiments describedabove. Thus, one can envision a detection device in which sensors arelocated only on one side of the vehicle, to monitor a modification ofthe surface solely on the side concerned.

Besides, all or part of the sensors can be laterally oriented towardsthe outside of the vehicle.

In particular, the sensors can be inclined towards the front or the backand/or towards a side of the vehicle with respect to the vertical.

Preferably, the inclination angle of the sensors with respect to thevertical is substantially equal to or above to the half angle A of theircone of vision 7. The cone of vision 7 of a sensor constitutes theangular reception window of the sensor (FIG. 2).

Preferably, the sensors are inclined with respect to the vertical at anangle comprised between about 5 and about 45 degrees and preferablyequal to about 15 degrees.

The orientation of the sensors defined above associates a good detectionquality of the ground with a precocious detection. Indeed, one noticesthat the size, the shape and the position obtained by the points of aimon the ground of the signals emitted by the sensors improve thedetection quality of the system, as compared to the prior art.

Preferably, the surface on the ground aimed at by a sensor describes asubstantially elliptical or circular track having a diameter in theorder of about 5 to about 10 cm. In addition, the sensors are preferablylocated at a height above the ground comprised between 15 cm and 1 m.

Referring to FIG. 6, the detection device can be used to warn the driverof a possible drifting by the vehicle from its trajectory. As a functionof information delivered by the sensors c1 to cn, the data processingmeans 2 can activate security means 9 such as means for signaling to theoutside (blinkers, for example), or to the vehicle user (light and/orsound and/or tactile warning).

Advantageously, activation or not of the security means 9 can also beconditioned by information M representative of the start-up or not ofthe detection system (switch, for example), and/or as a function of thespeed V of the vehicle, and/or as a function of an activated state S ornot of the vehicle blinkers.

This is to say that the monitoring and security system can include aswitch to control its start-up or its shut down, which can be actuatedby the vehicle user.

One can also envision an activation of the monitoring and alert deviceonly when the speed V of the vehicle is above a threshold in the order,for example, of 80 km/h.

Preferably also, the data processing means activate the security means 9only when a crossing is detected quasi simultaneously on both sides ofthe vehicle. In this manner, the normal crossing of a transverse line isnot signaled to the vehicle user.

Similarly, the alert and security means 9 can be activated only when thedetection of an abnormal discontinuity by a first sensor is confirmed byat least a second measurement made by an adjacent sensor.

Finally, even though the invention has been described in connection withparticular embodiments, it includes all the technical equivalents to themeans described.

1. Device for the detection of a running surface for a vehicle,comprising a plurality of sensors designed to be oriented towards therunning surface to determine modifications thereof, means for processingdata concerning information collected by the sensors, wherein at leastpart of the sensors are relatively arranged such that the transversedistances separating two adjacent points of aim on the ground of sensorsincrease in the direction of a longitudinal axis and along a directionsubstantially perpendicular to this axis.
 2. Detection device accordingto claim 1, which comprises at least five sensors.
 3. Detection deviceaccording to claim 1, wherein the sensors are located on both sides of amedian longitudinal axis, and the transverse distances between thepoints of aim on the ground of the sensors are substantially symmetricalwith respect to this axis.
 4. Detection device according to claim 1,wherein the transverse distance dn in cm separating two adjacent pointsof aim on the ground of sensors is given by the formula dn=k.R^(n),where n is the serial number of the point of aim on the ground in thedirection of the longitudinal axis, R is a first constant multiplicativecoefficient comprised between about 1 and about 2, and k is a secondconstant coefficient comprised between about 5 and about
 50. 5.Detection device according to claim 1, wherein the transverse distancedn in cm separating two adjacent points of aim on the ground of sensorsis given by the formula${{dn} = {{L2} \cdot \left( \frac{E + {L1}}{E + {2c}} \right)^{n}}},$ soas to detect in particular a discontinuous marking line on the ground,and where n is the serial number of the point of aim on the ground inthe direction of the longitudinal axis, L1 is the length in cm of a dashof the discontinuous line, L2 is the width in cm of a dash of thediscontinuous line, E is the distance in cm separating two consecutivedashes, and c is a determined constant defining a detection securitymargin in cm.
 6. Vehicle using a detection device according to claim 1,comprising a plurality of sensors oriented towards the running surfaceto determine modifications thereof, means for processing data concerninginformation collected by the sensors, wherein at least part of thesensors are relatively arranged such that the transverse distancesseparating two adjacent points of aim on the ground of sensors increasefrom the outside towards the inside of the vehicle along a directionsubstantially perpendicular to the median longitudinal axis of thevehicle.
 7. Vehicle according to claim 6, wherein the sensors arelocated on both sides of the median longitudinal axis of the vehicle,and the transverse distances between the points of aim on the ground ofthe sensors are substantially symmetrical with respect to this axis. 8.Vehicle according to claim 6, wherein the transverse distance dn in cmseparating two adjacent points of aim on the ground of sensors is givenby the formula dn=k.R^(n), where n is the serial number of the point ofaim on the ground in the direction of the longitudinal axis, R is afirst constant multiplicative coefficient comprised between about 1 andabout 2, and k is a second constant coefficient comprised between about5 and about
 50. 9. Vehicle according to claim 6, wherein the transversedistance dn in cm separating two adjacent points of aim on the ground ofsensors is given by the formula${{dn} = {{L2} \cdot \left( \frac{E + {L1}}{E + {2c}} \right)^{n}}},$ soas to detect in particular the position of the vehicle with respect to adiscontinuous marking line on the ground, and where n is the serialnumber of the point of aim on the ground of a sensor from the outsidetowards the inside of the vehicle, L1 is the length in cm of a dash ofthe discontinuous line, L2 is the width in cm of a dash of thediscontinuous line, E is the distance in cm separating two consecutivedashes, and c is a determined constant defining a detection securitymargin in cm.
 10. Vehicle according to claim 6, which comprises elevensensors.
 11. Vehicle according to claim 6, wherein at least part of thesensors are oriented laterally towards the outside of the vehicle. 12.Vehicle according to claim 6, wherein at least part of the sensors areinclined with respect to the vertical at an angle substantially equal toor above the half-angle of their cone of vision.
 13. Vehicle accordingto claim 6, wherein at least part of the sensors are inclined withrespect to the vertical at an angle comprised between about 5 and about45 degrees.
 14. Vehicle according to claim 6, wherein at least part ofthe sensors are disposed in the front bumper of the vehicle. 15.Detection device according to claim 4, wherein R is comprised betweenabout 1 and about 1.2.
 16. Vehicle according to claim 8, wherein R iscomprised between about 1 and about 1.2.